Because of the huge initials. KICK sustained well from Tuesday-Thursday. Now the euphoria has gone down, the business is happening just another normal working day. Majority of the people have caught the film in the first 7 days itself. Now, all you get is the ones who didn't catch the film in the last week & the ones who are repeat audience.
That's why 8cr or 9cr is a strong figure. Since the top grosser on 2nd friday is 3 Idiots but it was a holiday for 3 Idiots. That's why the numbers are considered strong.